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Arbitrary control of photon flow is of fundamental significance in many applications of light. Here, we propose a new approach that can trap, store, and move the signal photons to arbitrary desired place, just like what optical tweezers do on micro particles. In addition, the trapped photons can also be released at a given direction. The mechanism is based on an ultrahigh- Q nanocavity formed by two dynamically-generated potential barriers in a photonic crystal (PC) waveguide. Different from the traditional fixed ultrahigh- Q nanocavities, this new-type cavity can be formed instantaneously at any moment and any position in a PC waveguide, and is completely movable while keeps ultrahigh Q factor simultaneously. These novel features make controlling the flow of light like an optical tweezer possible, and open up new opportunities for dynamic lightâ€"matter interactions and on-chip optical signal processing. [ABSTRACT FROM AUTHOR]

Controlling the flow of light on-chip is of great importance for quantum computing and optical signal processing. In this paper, we present a theoretical study to reveal the underlying physics of how to effectively trap, store and release a signal pulse, and eventually break the delay-bandwidth limit, based on controllable EIT-like effect in dynamically tuned standing-wave cascaded nanocavities. Using this mechanism, we design a compact silicon photonic crystal system with long storing time and a delay-bandwidth product over 460, which is about two orders of magnitude greater than the reported results obtained by other methods based on static resonator system, and the trapped signal pulse can be released on demand. [ABSTRACT FROM AUTHOR]

We present a simple yet effective approach to realize all-optical diode (AOD) based on an asymmetric nanocavity–waveguide (WG) structure. We show that by adjusting the distance between the nonlinear nanocavity and its surrounding rods, the transmission characteristics of the input and output WGs (which are equivalent to two F–P cavities with different lengths) can be precisely tuned, and as a result, the coupling strengths between the nanocavity and its connected WGs become quite different. This makes the excitation of the bistable state inside cavity is sensitive to the launching direction of the signal light, and makes the nonreciprocal transmission of the signal light possible. In this way, the maximum transmission contrast over 20dB can be achieved for either forward or backward conducted AOD, with a broad operation bandwidth over 5 nm. The approach proposed here is promising in the fields of advanced photonic circuits, all-optical information processing, and optical communications. [ABSTRACT FROM AUTHOR]